House construction of hollow panels with double channel peripheral edge closure members



April 1966 c. G. STRANDLUND ETAL 3,

HOUSE CONSTRUCTION OF HOLLOW PANELS WITH DOUBLE CHANNEL PERIPHERAL EDGECLOSURE MEMBERS Filed July 26, 1962 6 Sheets-Sheet 1 INVENTORS ap/ffr/zJ/a4 0 9 dfiip/es M Sea/yep wwzw April 1966 c. G. STRANDLUND ETAL3,

HOUSE CONSTRUCTION OF HOLLOW PANELS WITH DOUBLE CHANNEL PERIPHERAL EDGECLOSURE MEMBERS I Filed July 26, 1962 6 Sheets-Sheet 2 1 I l l IINVENTORS CJP/ STraric/finyd 0 ZZEEMEZZZ 6 Sheets-Sheet 5 Apnl 5, 1966c. G. STRANDLUND ETAL HOUSE CONSTRUCTION OF HOLLOW PANELS WITH DOUBLECHANNEL PERIPHERAL EDGE CLOSURE MEMBERS Filed July 26, 1962 INVENTORS62,4 6. kmfld/ a q.

A ril 5, 1966 HOUSE CONSTRUCTION OF HOLLOW CHANNEL PERIPHERAL EDGE FiledJuly 26, 1962 I c. e. STRANDLUND ETAL 3,243,929 PANELS WITH DOUBLECLOSURE MEMBERS 6 Sheets-Sheet 4 Fig 5 I INVENTORS wWM/M April 5, 1966c. G. STRANDLUND ETAL 3,

HOUSE CONSTRUCTION OF HOLLOW PANELS WITH DOUBLE CHANNEL PERIPHERAL EDGECLOSURE MEMBERS Filed July 26, 1962 1 I III]!!! 6 Sheets-Sheet 5 ak/61f'rand/ /fld q BY Chow s W, baa/ye- WMEZQA 1 April 1966 c. G. STRANDLUNDETAL 3,

HOUSE CONSTRUCTION OF HOLLOW PANELS WITH DOUBLE CHANNEL PERIPHERAL EDGECLOSURE MEMBERS Filed July 26, 1962.

6 Sheets-Sheet 6 INVENTORS Car/Q St'kaIZJ/UHQ 4 United States PatentHDUSE CONSTRUCTION OF HOLLQW PANELS WITH DOUBLE CHANNEL PERIPHERAL EDGECLGSURE MEMBERS Carl G. Strandlund, Ann Arbor, and Charles W. Sawyer,

Plymouth, Mich, assignors to Strandlund Homes Corporation, Ypsilanti,Mich, a corporation of Delaware Filed July 26, 1962, Ser. No. 212,553 7Claims. (Cl. 52-234) This invention relates to prefabricated buildingstructures, and in particular to dwellings. In recent times this hasbeen a field involving a great measure of activity, and acorrespondingly large number of proposed approaches toward solution ofthe problems involved. As in all modern technology, the basic end soughtis economy of time, material, labor and cost.

In spite of the importance of mass production, the innumerable proposalshave had relatively little noticeable impact in the technology offabricating structures and, beyond a current trend toward the use ofprefabricated roof trusses and, to a lesser extent, the use of sectionsof preassembled wall studding, the construction work still remainslargely an on-site project of step-wise erect-ion, with mass productiondepending, for the most part on progressive construction by teams ofspecialists, working in succession.

According to the present invention, all of the essential elements of thebuilding, including exterior roof and siding, and interior wallsurfaces, are capable of prefabrication at the factory, with simpleassembly at the building site, through interlocking features and easybonding. No ordinary fasteners, such as nails, are required, and nocutting and fittings is involved. Under the system herein described,entire exterior walls, as well as partitions, are merely set in place ona slab, in interconnecting relationship, and the roof laid in place.This is made possible by the general scheme of construction of theprefabricated units, to be hereinafter described in detail, and whichinvolve, generally, a sandwich type of wall section, having one-piecepanels on the two sides, enclosing an inner filler, with inner ribreinforcements of channel section, located at door and window openingsas well as at spaced points along the wall section, and with edgeinserts on the four sides, closing the ends of the panels, and shapedexteriorly for cooperative mating engagement with edge members ofadjacent units of the building structure. As will be seen, the matingedges comprise 'various shapes corresponding to the different situationsinvolved in various parts of the structure, and generally speaking theseshapes will be different on the four sides of any given section or unitof the structure. However, consistent with the necessary or desirablevariation, the number of distinct parts represents a satisfactoryminimum.

It is, therefore, a general object of the invention to provideprefabricated units for a building, which may be constructed in theirentirety, and in final form at the factory, so that building erectioninvolves only assembly of the units. More particularly, it is an objectto provide entire wall sections, and like units, in prefabricated form.Another object is to provide for erection of buildings withprefabricated units, without the use of ordinary fastening means. Afurther object is to provide prefabricated building units havingbuilt-in studd'ing. A still further object is to provide a spaced-wallbuilding unit with edge closures having interlocking features. A relatedobject is to provide prefabricated roof units having characteristics asaforesaid, and which is assembled by simple laying of the units inplace. A further and more particular object is to provide prefabricatedbuilding units of plastic 3,243,929 Patented Apr. 5, 1966 material,which are locked in place at assembly by cementing, or a like process.

Additionally, it is an object to provide prefabricated wall unit-s inwhich the reinforcing elements, including the edge closure members, aregenerally of channel-form section, as contrasted with pieces of solidsection, whereby, not only is high strength maintained, with loweredweight, but a great variety of dove-tailing forms is easily attained.

Yet another object is to provide framing for door and window openingswhich is related to the edge closure pieces referred to above.

These and other ends, which will be readily apparent, are attained insatisfactory measure by the present in vention, as more fully describedin the specification to follow, and as illustrated in the drawings, inwhich:

FIGURE 1 is a front elevational view of a house constructed ofprefabricated wall sections according to the invention;

FIGURE 2 is a top plan view of the house of FIGURE 1, with portions ofthe roofs removed to show interior structure and arrangement;

FIGURE 3 is a sectional view taken on the line 3-3 of FIGURE 2;

FIGURE 4 is an enlarged sectional view taken on the line 4-4 of FIGURE2, and foreshortened in both horizontal and vertical directions;

FIGURE 5 is a sectional view, enlarged, of a typical, outside cornerjoint, taken on the line 5-5 of FIG- URE 1;

FIGURE 6 is an elevational view, enlarged in scale, and foreshortened,of a typical inside corner, taken on the line 6 6 of FIGURE 2;

FIGURE 7 is a sectional view through the four-way corner joint, taken onthe line 7-7 of FIGURE 6;

FIGURE 8 is a view of an outer wall panel, enlarged, taken on the line88 of FIGURE 2, and illustrating male and female, vertical edgeclosures;

FIGURE 9 is a horizontal sectional view, on further enlarged scale, andforeshortened, taken on the line 9-9 of FIGURE 8;

FIGURE 10 is a vertical sectional view, also to enlarged scale, andforeshortened, taken on the line 10-10 of FIGURE 8;

FIGURE 11 is a view similar to the left end portion of FIGURE 9, andshowing a different form of edge closure;

FIGURE 12 is a sectional view taken on the line 1212 of FIGURE 4;

FIGURE 13 is an enlarged, sectional view, taken on the line 1313 ofFIGURE 1; and

FIGURE 14 is an enlarged, sectional view, taken on the line 14-14 ofFIGURE 1.

Referring to the drawings by characters of reference, there is shown, inFIGURES 1 to 3, an assembled house, of generally L-form, comprising aliving area rectangle 10, constituting the leg of the T, and atransverse, bedroom area rectangle 12, constituting the cross member ofthe T. Due to the small size of the scale, only general outlines of thestructure are indicated in FIGURE 2.

The living wing 16 is made up of a total of six wall panels, with a pairof panels 14, 16 on the front side, joined at the line 17, a pair ofpanels 18, 20, on the rear side, joined at the line 21, an end, exteriorpanel 22, and an end, interior panel 24.

The bedroom wing is made up of panels comprising two panels 26, 28,extending from the living wing, a pair of end panels, 30, 32, and, onthe long, outer side, a set of three panels 34, 36, 38, with meetinglines 35, 37.

On the rear side, wing 10 has a large window 40, and two smaller windows42, 44, and a wide doorway 46, which may be provided with sliding glassdoors, leading to a patio. On the front side, wing 10 has two picturewindows, 48, 50, and two doorways 52, 54. An inner partition 56,extending lengthwise of Wing 10,'from inner, end wall 24 to the end wall58 of a utility room 60, is a bearing wall for roof support, and issupplemented by a lintel 62, which has support on end wall 22, and on animmediately located room divider 64, of L-form. A pair of alignedpartitions 66, 68, on opposite sides of wall 56, separate the room 60and the kitchen 70, respectively, from a pair of bathrooms 72, 74. Apartition 76 confines bathroom 72 and room 60, and has a doorway 78leading into the latter. A second doorway 80, in wall 56, leads from thekitchen to room 60. Wall 24 has doorways 82, 84, leading to therespective bathrooms, and a third door 86' leading into the hall outsideof the utility room 60. i

In the bedroom wing, a partition 88 defines a hallway .90, communicatingwith three bedrooms 92, 94 and 96, and closet structures 98, 100,constitutes partitions between the bedrooms. Panels 28 and 34 extendbeyond end wall 32 in projections 102, 104, adapted to receive storageshelves or cabinets, and to provide support for a carport roof 106,indicated in dash lines.

The roofs each comprise a series of panels laid in sideby-side relationalong the long dimensions of the wings. Thus, wing has a series ofidentical panels 108, extending from the line of the lintel 62, andoverhanging the wall panels 18 and 20, and a series of somewhat longerpanels 110 on the opposite side of the lintel, and overhanging walls' 14and 16. The lintel could also be located midway of the wing, in whichcase the roof panels 108 and 110 would be of equal length. The width ofwing 12 is such that only one set of roof panels 112 is required.

A typical wall unit is shown in FIGURES 8-10, in which middle panel 36of the bedroom wing has been selected for illustration. The complete,prefabricated panel is of the sandwich type, with surface boards 114,116, which may be of any conventional composition, such as pressedfiber, plaster board, or the like, and which are held in spaced relationby edge closure members, and internal, stud-like elements, presently tobe described in detail, the remaining space in the interior being filledby a porous, filler material 118,.which is preferably a foamed,polyurethane plastic. For simplicity, and for the sake of clarity as toother details, this filler has been shown only in FIGURES 9 and 10,being omitted from other figures.

In the fabrication of the wall unit at the factory, the surface boards,such as 114 and 116, are cut to sizeand provided with suitable openingsfor windows, doors and the like. The'spacing and reinforcing memberswhich may be metal but are preferably formed of strong plastic material,such as the studding 120, and edge closures 122 and 124 of FIGURES 9 and10, are then cemented or glued in place, in the required layout, on oneof the surface boards. If window or door openings are involved, edgeclosures, such as 126 of FIGURE 9, are also laid at the boundaries ofthe opening. Thereafter, the filler material 118 is flowed into theavailable spaces between the structural members, by suitable menas,after which the other surface board is laid on the unit, and heat andpressure applied. During this curing stage the filler 118 becomes firmlyadhered to both surface board, rendering the entire wall section aunitary element, endowed with stability, strength and permanence. It is,furthermore, of exact size, as predetermined for the building scheme,and needs only to be stood up in its proper location, and secured byadhesives. This construction is typical, and basic to all wall units,the only distinction among the several units being the type of edgeclosures employed, which appeartin some variety, depending on the natureof the several joints, and typical examples of such joints will bedescribed hereinafter.

FIGURE 4 shows typical, vertical sections through both inner and outerwalls as well as the roof panels. The outer wall panel 16 is seen ascomprising the female edge closure strip 124 at both top and bottomedges. These channel form components, permanently secured together andspaced to provide a tubular, honeycomb structure. Thus, each stripcomprises an outer channel 128, with an inwardly dished, V-forrn bottom130, and an inner channel 132, secured by cementing in nested relationwithin the channel 128, and also having an inwardly dished portion 134in which the vertex of the V-section is received, and secured bycementing. Thus'constructed, the unit has great rigidity andstrength,.with minimum weight, and presents especial reinforcementagainst damage to the V-section, female joint member.

Anchorage for the wall is provided in a rabbet corner 136 of thebuilding slab 138, which receives a special strip 140, of hollowconstruction, secured in place by a mass of mastic or cement 142, andhaving a projecting, V-fo'rm ridge 144 which mates with V-trough 130 onthe bottom edge of the wall panel. With the panel thus in place, and themale and female parts secured as by cement, the wall is securelyanchored in place, especially against lateral movement, which ispositively prevented by the keying interlock.

The inside, bearing wall, 80, is also anchored in the slab 138, thelatter being provided with a channel 146, in which a strip 148,generally similar to the strip is secured by cement 142. This strip alsohas a V-ridge 144, mating with lower edge closures the same as in theouter wall. Each strip has a reinforcing, inner septum 150, under the V,and strip 148', which is symmetrical about the septum, has side channels152, for greater holding power. Only one of these appears in strip 140,on the inner side, and the outer side is provided with a pair of hooks154, adapted to receive cooperating hooks on an outside, trim strip 156..On the inside, a trim strip or baseboard 158, of hollow construction,is secured to the wall unit, by any convenient means, such as a bolt160, or a snap-on device, and one of these strips may be placed on eachside of the inside Wall 80.

The support for the roof panels is evident in FIGURE .4, wherein a panel110 is shown as having an inner end sharing the top edge of wall 80 withits companion panel .108, and supported on and overhanging the :outsidewall lar channel 166, in which is nested a boattail channel member 168,both being concave outwardly. The top edge of wall 80 has a generallysimilar closure member, with a channel having a central trough 171 and anested channel 172, but in this case, both are concave inwardly. Theopening between the inner edges of panels 108 and 110, is covered by acap strip'174, secured by bolts 176, passing through suitable b'ores inthe cap .and in the channels 170, 172, and a suitable sealant mate rial178 is provided under the edges of the cap. For

additional protection, the cap may have additional inner ribs 180,suitably sealed, and a sealant may also be provided under the outerwasher 182. v

The roof panels have inner, channel studs 120, at

suitable intervals, and their outer ends are closed by inwardly openchannels 184, over the collective, outer ends of which is placed afascia strip 186, having a. depending, extending, lower, looped edge1'87.

FIGURE 12 shows the longitudinal, or side joint between the roof panels.This is a stepped joint, witha generally S-form interlock. Consideringthe female member, to the left in FIGURE 12, the closure strip 187comprises an outer member having a flange 188 attached to the inner sideof upper surface board 114, an arcuately dished corner 190, aperpendicularly disposedsection 7 :192, an intermediate, diagonallydirected loop portion 194, and a terminal, perpendicularly directedflange 196. Partially mated with this element, to form the honeycombedclosure strip, is a second member having a flange 198 secured to aportion of flange 188, in face contact, a diagonal section 200, anintermediate trough 2112, receiving the bight of loop 194, a seconddiagonal section 204, an outwardly directed section 266, secured toinner board 116, in face contact, and a perpendicular, terminal section208, secured to the inside of the other terminal flange 196, in facecontact. Due to the generally stepped configuration of the edge closureelement, side edges of the two surface boards 114, 116, are staggered.

The male edge closure 289, which is stepped reentrantwise, forming aclaw in complementary relation to closure 187, has a top flange 210,secured to the underside of board 114, in face contact, an areuatelydished corner 211, in mirror-image relation to a corner 1%, aperpendicular, depending section 212, an intermediate section 214, of Scurvature, one loop 215 of which extends partly into loop 194, to lockthe parts against sidewise relative movement, and a second, andterminal, perpendicular section 216. Inwardly of the component justdescribed, the reinforcing component has an upper flange 218, aninwardly open, channel form part spanning the thickness of the panel,and having an upper, diagonal section 220, a medial, perpendicularsection 222, a lower, diagonal section 224, an outwardly directed, lowersection 226, secured to the inside of the lower board 116 in facecontact, and a terminal, inwardly directed flange 228, secured to theinner side of section 216, in face contact. It will be understood thatthe two types of closure members, 187 and 209, will be provided,respectiveiy, on opposite side edges of each roof panel, except in theend panels, which will have a closure and trim such as shown in thelongitudinal end of the panel in FIG- URE 4. A suitable sealant material230 is placed in the trough formed by arcuate corners 190 and 211, andin the event of leak for any reason, the space between loop 215 and loop194 serves as a drain channel. In this connection, it should be notedthat the roof will have a slight slope, as shown in FIGURE 4, in anydegree deemed necessary or desirable.

FIGURES 81() show a wall section which is used for attachment of otherwall sections to its respective ends, and therefore comprises the maleand female end closure members, 122, 124, respectively, of which thefemale section has already been described. The male section 122comprising spaced, inner and outer sheets, has an outwardly extendingV-ridge 232 with marginal portions 234, the two being similar to parts162, 164 shown in FIGURE 4. In this case, however, for attachment withinthe wall panel, the member has a pair of flanges 236, secured to theinner sides of boards 114, 116, in face contact, and secured within thischannel member, and also open inwardly, is an inner sheet in the form ofa reinforcing channel piece 238, spaced inwardly of the outer channelmember. At convenient locations, the channel studs 120 may be providedwith hook-form elements 240, for handling elements of the electricalwiring system.

The edge closures at the window opening 241 (shown in FIGURE 9, butomitted in FIGURE 8) are roughly similar to closure 122, and differtherefrom in the outer component 242, which has a stepped form ratherthan a V-ridge. The frame 244 of the window is preferably of metal andis generally L-form, with an inner flange 246, secured as by a screw 248to the shoulder of the piece 242, and with an inwardly directed hooksection 250, engaging the face of outer board 114, and sealed by asuitable strip 252. The element 244 further carries a channel member254, providing a step 256 for accommodating the window proper, and thecrack between this member and inside surface board 116 is covered by aflanged, channel-form trim strip 258, secured in any convenient manner,such as snap-fastener strip 259. Access to screws, such as 248 is hadthrough suitable openings in the member 244, which openings are closedby snap plugs 260. A similar arrangement, at the top of a window isshown in FIGURE 4.

In the case of vertical wall edges which are not to be joined to anotherwall edge, one of the channel studs 124 may be used for the edgeclosure, as shown in FIGURE 11.

As shown in FIGURE 13, the door jamb is generally similar to the windowhardware, except that the element 262 has a strip 264 extending throughthe door opening, and has an intermediate channel portion 266 forming adoor stop with an inner and an outer shoulder. A like element isemployed at the top of the door, as shown in FIGURE 14. An inside doorlintel is shown in FIGURE 6, wherein the same unit 126, which mounts thewindow hardware in FIGURE 9, is employed.

In the four-way joint shown in FIGURE 7, special pieces are employed.Herein, the hallway door jamb 268 is secured to wall 16 by screws 270,and to wall panels 24 and 28 by screws 272. The end closure of panel 16comprises a channel 274, in which is secured a nested, clawform channel276. The end closures 278 in panels 24, 28, are generally similar toclosure 126 of FIGURE 6, except that they have bevelled corners 280,which receive, in nested relationship, the tapered outer end of one ofthe claw-form strips 276, which is secured by screws 282 in ashouldered, channel member 284, which constitutes a door stop.

An outside corner joint is shown in FIGURE 5. Here, one panel, 22, isprovided with a channel end closure 128, and the panel 14 has agenerally similar channel closure, modified by provision of an extendinglip or ridge, 286 on its outer side. The two panels are joined by astrip 288 of L-form section, secured by screws 290. A corner trim strip292, also of generally L-form, has a hooked end 294 interengaging lip286, and is secured by screws 296 to a hooked portion 298 of theconnecting member 288.

From the foregoing description, it will be apparent that the objectsenumerated at the outset are attainable in ample measure by the featuresof construction embodied in the present invention. Off-site constructionof entire walls, to final dimensions, and with doorways and windowopenings framed, makes possible a rapid erection at the building site,without need for fitting, cutting, trimming, or requirement for skilledlabor. In addition, the use of interlocking or interfitting edgeclosures, to gether with the adaptability of plastic structural membersfor attachment by adhesion, further expedite the job of erection.

Generally speaking, whereas a certain preferred, general embodiment, andpreferred variants among the subcombinations of structural elements havebeen shown and described, various other modifications will becomeapparent, in the light of this disclosure, and the invention should nottherefore, be deemed as limited, except insofar as shall appear from thespirit and scope of the appended claims.

We claim:

1. In a building assembled from prefabricated wall and roof unitsincluding outer wall panels, roof panels, and inner partition panels, aplurality of structural units, each unit comprising a pair of spaced,parallel, surface boards having edge closure members throughout theperiphery of the unit, plastic structural members of channel form,located in parallel spaced relation within the unit, having theirchannel flanges adhesively secured to the inner faces of said boards anda solid, foamed, plastic material contained in the spaces within saidunit, said edge closure members each comprising a plurality of plasticmembers of substantially uniform thickness and of generally channelshape, the webs thereof being at least partly spaced apart, the flangesof at least one of said channels being adhesively secured to the inneredge faces 7c of said boards and the flanges of each of said channelsbeing secured adhesively to each other interiorly of said boards, theoutwardly facing portions of exposed channel webs of mating panel unitsbeing formed for interfitting relationship.

2. The structure according to claim 1 wherein, of the plurality of edgeclosure channels there is one having its flanges directly secured to theinner edge faces of the boards and another having the outer faces of itsflanges secured to the inner faces of the one channel, the webs of thetwo channels being secured together at their midpoints but divergingthence toward the junctures of the flanges and webs, whereby the web ofthe one channel is braced by the web of the other.

3. The structure according to claim 1 wherein the edge closure channelsface inwardly of units which they close.

4. The structure according to claim 3 wherein, of the plurality of edgeclosure channels there is one having its flanges directly secured to theinner edge faces of the boards and another having the outer faces of itsflanges secured to the inner faces of the one channel, the webs of thetwo channels being secured together at their midpoints but divergingthence toward the junctures of the flanges and webs, whereby the web ofthe one channel is braced by the web of the other.

'5. The structure according to claim 3 wherein, of the plurality of edgeclosure channels, the exposed one has its flanges directly secured tothe inner faces of the boards, the web thereof having a stepped,L-shape,.there being a second, interior channel having the-externalfaces of its flange secured to the internal faces of the exposedchannel.

6. The structure according to claim 3 wherein, of the plurality of edgeclosure channels, the exposed one has its flanges directly secured tothe inner faces of the.

boards, the web thereof having a stepped reentrant shape forming a claw,there being a second interior channel having the external faces of itsflanges secured to the interiorfaces ofthe exposed channel and a portionof it web secured to the web of the exposed channel.

7. The structure according to claim 3 wherein, of the plurality of edgeclosure channels, theexposed one has its flanges directly secured toithe inner faces of t he boards, the web thereof having a first portion,adjacent one board, perpendicular to its adjacent flange, a secondadjacent portion at right angles to the first portion and.

of its flanges secured to the interior faces of the exposed channel anda portion of its web secured to the web of the exposed channel.

References Cited by the Examiner UNITED STATES PATENTS 2,048,457 7/1936Mauser 2 52580 2,114,388 4/1938 Killion 52 242 2,142,305 1/1939 ,Davis52 -'-589 2,156,347 5/1939 McLaughlin 52l463l 2,177,699 10/1939 Fisher52 -236: 2,339,220 1/ 1944 Crowley 52285 2,358,396 9/1944 Hogan" 524092,691,432 10/ 1954 Klein et a1. -52] +584- 2,858,580. 11/1958 Thompsonet al 5240 7 2,927,665 3/1960 Hauf 52262 2,963,825 12/1960 Douglas,52-94. 2,982,380 -5/1961 Rose 52578 3,003,810 10/1961 Kloote et al52309 X 3,031,043 4/1962 5290 X 5/1962 Schubach a' 52288 X:-

3,034,824 FOREIGN PATENTS 1,256,945 2/1961 France. 7 a

901,935 7/1962 Great Britain.

FRANK L. ABBoTT, Primary Examiner. JAcoB L. NACKENOFF, Examiner.

A: C. PERHAM, Assistant Examiner.

1. IN A BULDING ASSEMBLED FROM PREFABRICATED WALL AND ROOF UNITSINCLUDING OUTER WALL PANELS, ROOF PANELS, AND INNER PARTITION PANELS, APLURALITY OF STRUCTURAL UNITS, EACH UNIT COMPRISING A PAIR OFSPACED,PARALLEL, SURFACE BOARDS HAVING EDGE CLOSURE MEMBERS THROUGHOUTTHE PERIPHERY OF THE UNIT, PLASTIC STRUCTURAL MEMBERS OF CHANNEL FORM,LOCATED IN PARALLEL SPACED RELATION WITHIN THE UNIT, HAVING THEIRCHANNEL FLANGES ADHESIVELY SECURED TO THE INNER FACES OF SAID BOARDS ANDA SOLID, FOAMED, PLASTIC MATERIAL CONTAINED IN THE SPACES WITHIN SAIDUNIT, SAID EDGE CLOSURE MEMBERS EACH COMPRISING A PLURALITY OF PLASTICMEMBERS OF SUBSTANTIALLY UNIFORM THICKNESS AND OF GENERALLY CHANNELSHAPE, THE WEBS THEREOF BEING AT LEAST PARTLY SPACED APART, THE FLANGESOF AT LEAST ONE OF SAID CHANNELS BEING ADHESIVELY SECURED TO THE INNEREDGE FACES OF SAID BOARDS AND THE FLANGES OF EACH OF SAID CHANNELS BEINGSECURED ADHESIVELY TO EACH OTHER INTERIORLY OF SAID BOARDS, THEOUTWARDLY FACING PORTIONS OF EXPOSED CHANNEL WEBS OF MATING PANEL UNITSBEING FORMED FOR INTERFITTING RELATIONSHIP.